Dr. Murai Éva szerk.: Parasitologia Hungarica 16. (Budapest, 1983)

Diagnosis. Diplodiscinae. Body cylindrical, pharynx with anterior sphincter, Pseudodiplodiscus-type. Primary pharyngeal sacs rudimental, embedded in wall of pharynx. Oesophagus long, oesophageal bulb present, weakly developed; caeca terminating middle part of body. Genital opening at level of bifurcation, with weakly developed musculature and without genital sucker. Ovary removed towards left side, posttesticular, postcaecal. Testis single, cirrus pouch poorly developed. Eggs numerous, operculated. Vitellaria lateral, at middle part of body. Acetabulum simple, without accessory sucker or other formations. Opening of Laurer' s canal in front of excretory pore. Type and single species: Pseudodiplodiscus cornu (Diesing, 1836) Szidat, 1939 (Fig. 25). Subfamily OPISTHODISCINAE Skrjabin, 1949 The first representative of this group of amphistomes was described by COHN (1904) from Europe under the name Opisthodiscus diplodiscoides. MÉHELYI (1929) introduced the subspecies O. diplodiscoides nigrivasis on the basis of the dark content in its alimentary tract. This subspecies was raised to species rank by DOLLFUS (1951), named as O. nigrivasis. ODENING (1959) was of the opinion that the genus comprises COHN's species and MEHELY ' s subspecies, of which specific status was also affirmed by himself. GRABDA-KAZUBSkA (1980) gave a detailed description of its synonymy and geographical distribution and she came to the conclusion that this genus consists of one species, O. diplodiscoides

. In the figure attached by COHN (1904) to the description there was reaUy one testis, in the text, however, two were mentioned. In our experiments the presence of two testes was observed. The writer agrees with GRABDA-KAZUBSKA'

s (1980) opinion so as to the monotypy of this genus. Reports about recovery of this species and genus outside Europe were as follows: Opistho discus subclavatus (sic) (PALLAS, 1760; FUKUI, 1923) from Japanese salamander by PEARSE (1932) and an Opisthodiscus sp

. from the Ivory Coast by Maeder (1969). As neither description nor figure was attached to PEARSE'

s text it is difficult to establish what species it is. Nevertheless, in FUKUI'

s paper (1923) which PEARSE refers to D. subclavatus was reported. As to MAEDER* s (1969) species, one specimen was found and closer identification could not be carried out. DOLLFUS (1951) described an amphistome sample having two testes from the Maoroccan Rana ridibunda under the name D. subclavatus schistorchis. Designation of the subspecies was based on LOOSS's (1892) statement that the single testis of D. subclavatus can originate from fusion but it can also be behind and the latter case refers to this subspecies. As the phenomenon of the "fusion" was clarified above, this subspecies is synonymous with O. diplodiscoides. SKRJABIN (1949) raised the genus to subfamilial rank, including the single genus Opistho discus, on the basis of the permanent existance of two testes and the absence of the oesophageal bulb. The false interpretation of the latter feature was demonstrated above. According to our conception, however, the subfamily consists of two genera, Opisthodiscus and Me galodiscus. Diagnosis. Diplodiscidae. Body pyriform. Pharynx with different histomorphological structure, primary pharyngeal sacs prominent. Oesophagus short, oesophageal bulb present. Two testes, median or horizontal in middle part of body. Cirrus pouch small, genital opening at bifurcation or at base of pharynx. Ovary posttesticular, median. Vitellaria extending along caeca or posterior part of them. Uterine coils intercoecal or somewhat extracaecal. Egg numerous, embryonated. Acetabulum well developed with accessory sucker or central prominence. Parasitic in rectum of amphibians. Type genus: Opisthodiscus Cohn, 1904